Number Density Of Sources Research Articles

THE ROLE OF STRUCTURED MAGNETIC FIELDS ON CONSTRAINING PROPERTIES OF TRANSIENT SOURCES OF ULTRA-HIGH-ENERGY COSMIC RAYS

We study how the properties of transient sources of ultra-high-energy cosmic rays (UHECRs) can be accessed by exploiting UHECR experiments, taking into account the propagation of UHECRs in magnetic structures which the sources are embedded in, i.e., clusters of galaxies and filamentary structures. Adopting simplified analytical models, we demonstrate that the structured extragalactic magnetic fields (EGMFs) play crucial roles in unveiling the properties of the transient sources. These EGMFs unavoidably cause significant delay in the arrival time of UHECRs as well as the Galactic magnetic field, even if the strength of magnetic fields in voids is zero. Then, we show that, given good knowledge on the structured EGMFs, UHECR observations with high statistics above $10^{20}$ eV allow us to constrain the generation rate of transient UHECR sources and their energy input per burst, which can be compared with the rates and energy release of known astrophysical phenomena. We also demonstrate that identifying the energy dependence of the apparent number density of UHECR sources at the highest energies is crucial as a clue to such transient sources. Future UHECR experiments with extremely large exposure are required to reveal the nature of transient UHECR sources.

THE EVOLUTION OF Lyα-EMITTING GALAXIES BETWEENz= 2.1 ANDz= 3.1

We describe the results of a new, wide-field survey for z=3.1 Ly-alpha emission-line galaxies (LAEs) in the Extended Chandra Deep Field South (ECDF-S). By using a nearly top-hat 5010 Angstrom filter and complementary broadband photometry from the MUSYC survey, we identify a complete sample of 141 objects with monochromatic fluxes brighter than 2.4E-17 ergs/cm^2/s and observers-frame equivalent widths greater than ~ 80 Angstroms (i.e., 20 Angstroms in the rest-frame of Ly-alpha). The bright-end of this dataset is dominated by x-ray sources and foreground objects with GALEX detections, but when these interlopers are removed, we are still left with a sample of 130 LAE candidates, 39 of which have spectroscopic confirmations. This sample overlaps the set of objects found in an earlier ECDF-S survey, but due to our filter's redder bandpass, it also includes 68 previously uncataloged sources. We confirm earlier measurements of the z=3.1 LAE emission-line luminosity function, and show that an apparent anti-correlation between equivalent width and continuum brightness is likely due to the effect of correlated errors in our heteroskedastic dataset. Finally, we compare the properties of z=3.1 LAEs to LAEs found at z=2.1. We show that in the ~1 Gyr after z~3, the LAE luminosity function evolved significantly, with L* fading by ~0.4 mag, the number density of sources with L > 1.5E42 ergs/s declining by ~50%, and the equivalent width scale-length contracting from 70^{+7}_{-5} Angstroms to 50^{+9}_{-6} Angstroms. When combined with literature results, our observations demonstrate that over the redshift range z~0 to z~4, LAEs contain less than ~10% of the star-formation rate density of the universe.

Submillimetre source counts in the fields of high-redshift galaxy clusters

We present a submillimetre survey of seven high-redshift galaxy clusters (0.64 < z < 1.0) using the Submillimetre Common-User Bolometer Array (SCUBA) at 850 and 450 m. The targets, of similar richness and redshift, are selected from the Red-sequence Cluster Survey (RCS). We use this sample to investigate the apparent excess of submillimetre source counts in the direction of cluster fields compared to blank fields, as seen in the literature. The sample consists of three galaxy clusters that exhibit multiple optical arcs due to strong gravitational lensing, and a control group of four clusters with no apparent strong lensing. A tentative excess of 2.7σ is seen in the number density of submillimetre sources within the lensing cluster fields compared to that in the control group. Ancillary observations at radio, mid-infrared, optical and X-ray wavelengths allow for the identification of counterparts to many of the submillimetre luminous galaxies (SMGs), and provide improved astrometry and redshift constraints. Utilizing photometric redshifts, we conclude that at least three of the galaxies within the lensing fields have redshifts consistent with the clusters and implied infrared luminosities of ∼1012 L⊙. The existence of submillimetre cluster members may therefore be boosting source counts in the lensing cluster fields, which might be an effect of the dynamical state of those clusters. However, we find that the removal of potential cluster members from the counts analysis does not entirely eliminate the difference between the cluster samples. We also investigate possible occurrences of lensing between background submillimetre sources and lower redshift optical galaxies, though further observations are required to make any conclusive claims. Although the excess counts between the two cluster samples have not been unambiguously accounted for, these results warrant caution for interpreting submillimetre source counts in cluster fields and point source contamination for Sunyaev–Zel’dovich surveys.

Fast, large-volume, GPU-enabled simulations for the Ly forest: power spectrum forecasts for baryon acoustic oscillation experiments

High-redshift measurements of the baryonic acoustic oscillation (BAO) scale from large Lyα forest surveys represent the next frontier of dark energy studies. As part of this effort, efficient simulations of the BAO signature from the Lyα forest will be required. We construct a model for producing fast, large-volume simulations of the Lyα forest for this purpose. Utilizing a calibrated semi-analytic approach, we are able to run very large simulations in 1 Gpc3 volumes which fully resolve the Jeans scale in less than a day on a desktop PC using a graphics processing unit enabled version of our code. The Lyα forest spectra extracted from our semi-analytical simulations are in excellent agreement with those obtained from a fully hydrodynamical reference simulation. Furthermore, we find that our simulated data are in broad agreement with observational measurements of the flux probability distribution and 1D flux power spectrum. We are able to correctly recover the input BAO scale from the 3D Lyα flux power spectrum measured from our simulated data, and estimate that a Baryon Oscillation Spectroscopic Survey like 104 deg2 survey with ∼15 background sources per square degree and a signal-to-noise ratio of ∼5 per pixel should achieve a measurement of the BAO scale to within ∼1.4 per cent. We also use our simulations to provide simple power-law expressions for estimating the fractional error on the BAO scale on varying the signal-to-noise ratio and the number density of background sources. The speed and flexibility of our approach is well suited for exploring parameter space and the impact of observational and astrophysical systematics on the recovery of the BAO signature from forthcoming large-scale spectroscopic surveys.

On estimating Lyα forest correlations between multiple sightlines

The next frontier of Lyman-alpha forest studies is the reconstruction of 3D correlations from a dense sample of background sources. The measurement of 3D correlations has the potential to improve constraints on fundamental cosmological parameters, ionizing background models, and the reionization history. This study addresses the sensitivity of spectroscopic surveys to 3D correlations in the Lyman-alpha forest. We show that the sensitivity of a survey to this signal can be quantified by just a single number, a noise-weighted number density of sources on the sky. We investigate how the sensitivity of a spectroscopic quasar (or galaxy) survey scales as a function of its depth, area, and redshift. We propose a simple method for weighting sightlines with varying S/N levels to estimate the correlation function, and we show that this estimator generally performs nearly as well as the minimum variance quadratic estimator. In addition, we show that the sensitivity of a quasar survey to the flux correlation function is generally maximized if it observes each field just long enough to achieve S/N ~ 2 in a 1 A pixel on an L_* quasar while acquiring spectra for all quasars with L > L_*: Little is gained by integrating longer on the same targets or by including fainter quasars. We quantify how these considerations relate to constraints on the angular diameter distance, the curvature of space-time, and the reionization history.

THE GALACTIC BULGE SURVEY: OUTLINE AND X-RAY OBSERVATIONS

We introduce the Galactic Bulge Survey (GBS) and we provide the Chandra source list for the region that has been observed to date. Among the goals of the GBS are constraining the neutron star equation of state and the black hole mass distribution via the identification of eclipsing neutron star and black hole low-mass X-ray binaries. The latter goal will, in addition, be obtained by significantly enlarging the number of black hole systems for which a black hole mass can be derived. Further goals include constraining X-ray binary formation scenarios, in particular the common envelope phase and the occurrence of kicks, via source-type number counts and an investigation of the spatial distribution of X-ray binaries, respectively. The GBS targets two strips of 6x1 degrees (12 square degrees in total), one above (1<b<2 degrees) and one below (-2<b<-1 degrees) the Galactic plane in the direction of the Galactic Center at both X-ray and optical wavelengths. By avoiding the Galactic plane (-1<b<1 degrees) we limit the influence of extinction on the X-ray and optical emission but still sample relatively large number densities of sources. The survey is designed such that a large fraction of the X-ray sources can be identified from their optical spectra. The X-ray survey, by design, covers a large area on the sky while the depth is shallow using 2 ks per Chandra pointing. In this way we maximize the predicted number ratio of (quiescent) low-mass X-ray binaries to Cataclysmic Variables. The survey is approximately homogeneous in depth to an 0.5-10 keV flux of 7.7x10^-14 erg cm-2 s-1. So far, we have covered about two-thirds (8.3 square degrees) of the projected survey area with Chandra providing over 1200 unique X-ray sources. We discuss the characteristics and the variability of the brightest of these sources.

HerMES: detection of cosmic magnification of submillimetre galaxies using angular cross-correlation★

Cosmic magnification is due to the weak gravitational lensing of sources in the distant Universe by foreground large-scale structure leading to coherent changes in the observed number density of the background sources. Depending on the slope of the background source number counts, cosmic magnification causes a correlation between the background and foreground galaxies, which is unexpected in the absence of lensing if the two populations are spatially disjoint. Previous attempts using submillimetre (sub-mm) sources have been hampered by small number statistics. The large number of sources detected in the {\it Herschel} Multi-tiered Extra-galactic Survey (HerMES) Lockman-SWIRE field enables us to carry out the first robust study of the cross-correlation between sub-mm sources and sources at lower redshifts. Using ancillary data we compile two low-redshift samples from SDSS and SWIRE with <z> ~ 0.2 and 0.4, respectively, and cross-correlate with two sub-mm samples based on flux density and colour criteria, selecting galaxies preferentially at z ~ 2. We detect cross-correlation on angular scales between ~1 and 50 arcmin and find clear evidence that this is primarily due to cosmic magnification. A small, but non-negligible signal from intrinsic clustering is likely to be present due to the tails of the redshift distribution of the sub-mm sources overlapping with those of the foreground samples.

A bias in cosmic shear from galaxy selection: results from ray-tracing simulations

We identify and study a previously unknown systematic effect on cosmic shear measurements, caused by the selection of galaxies used for shape measurement, in particular the rejection of close (blended) galaxy pairs. We use ray-tracing simulations based on the Millennium Simulation and a semi-analytical model of galaxy formation to create realistic galaxy catalogues. From these, we quantify the bias in the shear correlation functions by comparing measurements made from galaxy catalogues with and without removal of close pairs. A likelihood analysis is used to quantify the resulting shift in estimates of cosmological parameters. The filtering of objects with close neighbours (a) changes the redshift distribution of the galaxies used for correlation function measurements, and (b) correlates the number density of sources in the background with the density field in the foreground. This leads to a scale-dependent bias of the correlation function of several percent, translating into biases of cosmological parameters of similar amplitude. This makes this new systematic effect potentially harmful for upcoming and planned cosmic shear surveys. As a remedy, we propose and test a weighting scheme that can significantly reduce the bias.

Inverse-Compton ghosts and double-lobed radio sources in the X-ray sky

In this study we predict the total distributions of powerful (FR II) active double-lobed radio galaxies and ghost sources, and their observable distribution in the X-ray sky. We develop an analytic model for the evolution of the lobe emission at radio and X-ray energies. During jet activity, a double radio source emits synchrotron radiation in the radio and X-ray emission due to inverse-Compton (IC) upscattering by gamma~10^3 electrons of the cosmic microwave background. After the jets switch off, the radio luminosity (due to higher gamma electrons) falls faster than the X-ray luminosity and for some time the source appears as an IC ghost of a radio galaxy before becoming completely undetectable in the X-ray. With our model, for one set of typical parameters, we predict radio lobes occupy a volume fraction of the universe of 0.01, 0.03, 0.3 at z=2 (during the quasar era) of the filamentary structures in which they are situated, for typical jet lifetimes 5*10^7 yr, 10^8 yr, 5*10^8 yr; however since the inferred abundance of sources depends on how quickly they fall below the radio flux limit the volume filling factor is found to be a strong function of radio galaxy properties such as energy index and minimum gamma factor of injected particles, the latter not well constrained by observations. We test the predicted number density of sources against the Chandra X-ray Deep Field North survey and also find the contribution to the unresolved cosmic X-ray background by the lobes of radio galaxies. 10-30 per cent of observable double-lobed structures in the X-ray are predicted to be IC ghosts. The derived X-ray luminosity function of our synthetic population shows that double-lobed sources have higher space densities than X-ray clusters at redshifts z>2 and X-ray luminosities above 10^44 erg s^-1.

DOES GALACTIC MAGNETIC FIELD DISTURB THE CORRELATION OF THE HIGHEST ENERGY COSMIC RAYS WITH THEIR SOURCES?

The propagation trajectories of the highest energy cosmic rays (HECRs) are deflected by not only intergalactic magnetic field but also Galactic magnetic field (GMF). These magnetic fields can weaken the positive correlation between the arrival directions of HECRs and the positions of their sources. In order to explore the effect of GMF on the expected correlation, we simulate the arrival distribution of protons with the energy above $6 \times 10^{19}$ eV taking several GMF models into account, and then test the correlation between the protons and their sources assumed in the simulation. The dependence of the correlation signals on GMF models are also investigated. The correlation can be observed by accumulating $\sim 200$ protons in a half hemisphere. Typical angular scale at which the positive signal of the correlation is maximized depends on the spiral component of GMF models. That angular scale is $\sim 5^o$ for bisymmetric spiral (BS) GMF models and $\sim 7^o$ for axisymmetric spiral (AS) GMF models if the number density of HECR sources, $n_s$, is $\sim 10^{-4}$ Mpc$^{-3}$. An additional vertical (dipole) component of GMF affects these angular scale by $0.5^o$ - $1^o$. The difference between the correlation signal for the BS models and that for the AS models is prominent in the northern sky. Significance of the positive correlation depends on source distribution. The probability that the number of simulated HECR events correlating with sources is smaller than the number of random events correlating with the same sources by chance is much less than $10^{-3}$ ($\sim 3\sigma$) in almost all the source distributions with $n_s = 10^{-4}$ Mpc$^{-3}$ under 200 protons detection, but $\sim 10\%$ of source distributions predicts the chance probability more than $10^{-3}$ in the AS GMF model. In addition, we also briefly discuss the effect of GMF for heavy-nuclei dominated composition.

The Herschel Multi-Tiered Extragalactic Survey: source extraction and cross-identifications in confusion-dominated SPIRE images

We present the cross-identification and source photometry techniques used to process Herschel SPIRE imaging taken as part of the Herschel Multi-Tiered Extragalactic Survey (HerMES). Cross-identifications are performed in map-space so as to minimise source blending effects. We make use of a combination of linear inversion and model selection techniques to produce reliable cross-identification catalogues based on Spitzer MIPS 24 micron source positions. Testing on simulations and real Herschel observations show that this approach gives robust results for even the faintest sources S250~10 mJy. We apply our new technique to HerMES SPIRE observations taken as part of the science demostration phase of Herschel. For our real SPIRE observations we show that, for bright unconfused sources, our flux density estimates are in good agreement with those produced via more traditional point source detection methods (SussExtractor; Savage & Oliver et al. 2006) by Smith et al. 2010. When compared to the measured number density of sources in the SPIRE bands, we show that our method allows the recovery of a larger fraction of faint sources than these traditional methods. However this completeness is heavily dependant on the relative depth of the existing 24 micron catalogues and SPIRE imaging. Using our deepest multi-wavelength dataset in GOODS-N, we estimate that the use of shallow 24 micron in our other fields introduces an incompleteness at faint levels of between 20-40 per cent at 250 micron.

Dark energy from large-scale structure lensing information

Wide area Large-Scale Structure (LSS) surveys are planning to map a substantial fraction of the visible universe to quantify dark energy through Baryon Acoustic Oscillations (BAO). At increasing redshift, for example that probed by proposed 21-cm intensity mapping surveys, gravitational lensing potentially limits the fidelity (Hui et al., 2007) because it distorts the apparent matter distribution. In this paper we show that these distortions can be reconstructed, and actually used to map the distribution of intervening dark matter. The lensing information for sources at z=1-3 allows accurate reconstruction of the gravitational potential on large scales, l <~ 100, which is well matched for Integrated Sachs-Wolfe (ISW) effect measurements of dark energy and its sound speed, and a strong constraint for modified gravity models of dark energy. We built an optimal quadratic lensing estimator for non-Gaussian sources, which is necessary for LSS. The phenomenon of "information saturation" (Rimes & Hamilton, 2005) saturates reconstruction at mildly non-linear scales, where the linear source power spectrum Delta^2 ~ 0.2-0.5. We find that steeper power spectra, saturate more quickly. We compute the effective number densities of independent lensing sources for LSS lensing, and find that they increase rapidly with redshifts. For LSS/21-cm sources at z ~ 2-4, the lensing reconstruction is limited by cosmic variance at l<~ 100.

Mid- and far-infrared luminosity functions and galaxy evolution from multiwavelengthSpitzerobservations up toz ~ 2.5

[Abridged]We exploit a large homogeneous dataset to derive a self-consistent picture of IR emission based on the time-dependent 24, 15, 12 and 8micron monochromatic and bolometric IR luminosity functions (LF) over the 0<z<2.5 redshift range. Our analysis is based on the combination of data from deep Spitzer surveys in the VVDS-SWIRE and GOODS areas. To our limiting flux of S(24)=400microJy our derived sample in VVDS-SWIRE includes 1494 sources, and 666 and 904 sources brighter than S(24)=80microJy are catalogued in GOODS-S and GOODS-N, respectively, for a total area of ~0.9 square degs. We obtain reliable optical identifications and redshifts, providing us a rich and robust dataset for our luminosity function determination. Based on the multi-wavelength information available, we constrain the LFs at 8, 12, 15 and 24micron. We also extrapolate total IR luminosities from our best-fit to the observed SEDs of each source, and use this to derive the bolometric LF and comoving volume emissivity up to z~2.5. In the 0<z<1 interval, the bolometric IR luminosity density evolves as (1+z)^3.8+/-0.4. Although more uncertain at higher-z, our results show a flattening of the IR luminosity density at z>1. The mean redshift of the peak in the source number density shifts with luminosity: the brighest IR galaxies appear to be forming stars earlier in cosmic time (z>1.5), while the less luminous ones keep doing it at more recent epochs (z~1 for L(IR)<10^11L_sun). Our results suggest a rapid increase of the galaxy IR comoving volume emissivity back to z~1 and a constant average emissivity at z>1. We also seem to find a difference in the evolution rate of the source number densities as a function of luminosity, a downsizing evolutionary pattern similar to that reported from other samples of cosmic sources.

PARTICLE MESH SIMULATIONS OF THE Lyα FOREST AND THE SIGNATURE OF BARYON ACOUSTIC OSCILLATIONS IN THE INTERGALACTIC MEDIUM

We present a set of ultra-large particle-mesh simulations of the LyA forest targeted at understanding the imprint of baryon acoustic oscillations (BAO) in the inter-galactic medium. We use 9 dark matter only simulations which can, for the first time, simultaneously resolve the Jeans scale of the intergalactic gas while covering the large volumes required to adequately sample the acoustic feature. Mock absorption spectra are generated using the fluctuating Gunn-Peterson approximation which have approximately correct flux probability density functions (PDFs) and small-scale power spectra. On larger scales there is clear evidence in the redshift space correlation function for an acoustic feature, which matches a linear theory template with constant bias. These spectra, which we make publicly available, can be used to test pipelines, plan future experiments and model various physical effects. As an illustration we discuss the basic properties of the acoustic signal in the forest, the scaling of errors with noise and source number density, modified statistics to treat mean flux evolution and misestimation, and non-gravitational sources such as fluctuations in the photo-ionizing background and temperature fluctuations due to HeII reionization.

Constraints on extragalactic point source flux from diffuse neutrino limits

We constrain the maximum flux from extragalactic neutrino point sources by using diffuse neutrino flux limits. We show that the maximum flux from extragalactic point sources is E^2(dN/dE) < 1.4 x 10^-9 (L_nu/2x10^43 erg/s)^1/3 GeV cm-^2 s^-1 from individual point sources with average neutrino luminosity per decade, L_nu. It depends only slightly on factors such as the inhomogeneous matter density distribution in the local universe, the luminosity distribution, and the assumed spectral index. The derived constraints are at least one order of magnitude below the current experimental limits from direct searches. Significant constraints are also derived on the number density of neutrino sources and on the total neutrino power density.

A GLOBAL AUTOCORRELATION STUDY AFTER THE FIRST AUGER DATA: IMPACT ON THE NUMBER DENSITY OF UHECR SOURCES

We perform an autocorrelation study of the Auger data with the aim to constrain the number density n{sub s} of ultrahigh energy cosmic ray (UHECR) sources, estimating at the same time the effect on n{sub s} of the systematic energy scale uncertainty and of the distribution of UHECR. The use of global analysis has the advantage that no biases are introduced, either in n{sub s} or in the related error bar, by the a priori choice of a single angular scale. The case of continuous, uniformly distributed sources is nominally disfavored at 99% CL and the fit improves if the sources follow the large-scale structure of matter in the universe. The best-fit values obtained for the number density of proton sources are within a factor {approx}2 around n{sub s} {approx_equal} 1 x 10{sup -4}Mpc{sup -3} and depend mainly on the Auger energy calibration scale, with lower densities being preferred if the current scale is correct. The data show no significant small-scale clustering on scales smaller than a few degrees. This might be interpreted as a signature of magnetic smearing of comparable size, comparable with the indication of a {approx}3 deg. magnetic deflection coming from cross-correlation results. The effects of somemore » approximations done on the above results are also discussed.« less

Detecting mass substructure in galaxy clusters: an aperture mass statistic for gravitational flexion

Gravitational flexion has recently been introduced as a technique by which one can map out and study substructure in clusters of galaxies. Previous analyses involving flexion have measured the individual galaxy-galaxy flexion signal, or used either parametric techniques or a KSB-type inversion to reconstruct the mass distribution in Abell 1689. In this paper, we present an aperture mass statistic for flexion, and apply it to the lensed images of background galaxies obtained by ray-tracing simulations through a simple analytic mass distribution and through a galaxy cluster from the Millennium simulation. We show that this method is effective at detecting and accurately tracing structure within clusters of galaxies on sub-arcminute scales with high signal-to-noise even using a moderate background source number density and image resolution. In addition, the method provides much more information about both the overall shape and the small-scale structure of a cluster of galaxies than can be achieved through a weak lensing mass reconstruction using gravitational shear data. Lastly, we discuss how the zero-points of the aperture mass might be used to infer the masses of structures identified using this method.

Towards Unravelling the Structural Distribution of Ultra-High-Energy Cosmic Ray Sources

We investigate the possibility that observations of ultra-high-energy cosmic-rays (UHECRs) in the near future may be able to unveil their local source distribution. We simulate the arrival distribution of UHE protons taking account of their propagation process in intergalactic magnetic field (IGMF) associated with the local structure actually observed around the Milky Way and investigate the similarity of the spatial patterns between the arrival distribution and the source distribution. We find that UHE protons above 10 19.8 eV are the best indicators for unravelling the source distribution within 100 Mpc, and the detection of about 500 events on the whole sky would realize the purpose for plausible IGMF strength and source number density. We also discuss the deflection of the trajectories of UHE protons by the Galactic magnetic field (GMF). In favored GMF models, the deflection angles are consistent with the angular scale of the positional correlation reported by the Pierre Auger Observatory except in th...

Implications to sources of ultra-high-energy cosmic rays from their arrival distribution

We estimate the local number density of sources of ultra-high-energy cosmic rays (UHECRs) based on the statistical features of their arrival direction distribution. We calculate the arrival distributions of protons above 10 19 eV taking into account their propagation process in the Galactic magnetic field and a structured intergalactic magnetic field, and statistically compare those with the observational results of the Pierre Auger Observatory. The anisotropy in the arrival distribution at the highest energies enables us to estimate the number density of UHECR sources as ∼10 −4 Mpc −3 assuming the persistent activity of UHECR sources. We compare the estimated number density of UHECR sources with the number densities of known astrophysical objects. This estimated number density is consistent with the number density of Fanaroff–Reily I galaxies. We also discuss the reproducibility of the observed isotropy in the arrival distribution above 10 19 eV. We find that the estimated source model cannot reproduce the observed isotropy. However, the observed isotropy can be reproduced with the number density of 10 - 2 – 10 - 3 Mpc - 3 . This fact indicates the existence of UHECR sources with a maximum acceleration energy of ∼10 19 eV whose number density is an order of magnitude more than that injecting the highest energy cosmic rays.

Toward Unravelling the Structural Distribution of Ultra‐High‐Energy Cosmic Ray Sources

We investigate the possibility that observations of ultra-high-energy cosmic rays (UHECRs) in the near future may be able to unveil their local source distribution, which will reflect observed local structures if their origins are astrophysical objects. In order to discuss this possibility, we calculate the arrival distribution of UHE protons taking into account their propagation process in intergalactic space, i.e., energy losses and deflections by the extragalactic magnetic field (EGMF). For a realistic simulation, we construct and adopt a model of a structured EGMF and UHECR source distribution, which reproduces the local structures actually observed around the Milky Way. The arrival distribution is compared statistically to the source distribution using a correlation coefficient. We find that UHECRs above 1019.8 eV are the best indicators for deciphering the source distribution within 100 Mpc, and the detection of about 500 events on all the sky would allow us to unveil the local structure of the UHE universe for plausible EGMF strength and source number density. This number of events could be detected by 5 years observation by the Pierre Auger Observatory.